In the 1950s, marijuana was known as the killer weed. Reefer madness. The steppingstone to heroin.
A decade later, many researchers decided the early warnings were overblown and slightly hysterical, contending that marijuana smoking was no more harmful than the occasional cocktail.
Today, the pendulum is swinging back, as recent research has turned up increasing evidence of health hazards associated with chronic marijuana smoking.
Adding to the concern is the sharply increased potency of the marijuana now in use in the United States. Some of the studies done in the past are now obsolete because the drug is so much stronger now. Even recent studies have been conducted with marijuana that is less potent than what is being sold today on the streets.
Today, as a result of sophisticated growing techniques, the average content of tetrahydrocannabinol, or THC, the active ingredient in marijuana, in top-grade sinsemilla (seedless) marijuana is about 7%, and some potent strains can be as high as 14%, according to Dr. Sidney Cohen, a professor of psychiatry at the UCLA Medical School and one of the nation's early marijuana researchers.
In contrast, only 10 years ago, the average THC content in marijuana bought on the street was 0.5% to 1%, Cohen said. And the THC content in marijuana used in clinical tests in the 1970s was 1% to 2%, he added.
'Ten Times Stronger'
"A lot of the stuff on the streets is now more than 10 times stronger than what people had been used to; it's almost a completely different drug," said Cohen, a drug consultant for the U.S. State Department. "But I've never seen any human studies that used 4% or 5% THC. . . . We may have to redo a lot of research. But even research with the lower-potency marijuana has indicated some real health problems."
Cohen in recent months surveyed marijuana research conducted during the past few years and wrote a paper for a congressional report on drug abuse. The following are some of his findings:
-THC causes changes in the reproductive systems of test animals.
-Marijuana smoking among pregnant women can adversely affect fetal development.
-Extensive lung damage has been documented in chronic marijuana smokers.
-THC has impaired the immune system in test animals and decreased resistance to infections.
-The already critical problem of drunken driving is exacerbated by marijuana smoking.
While little research has been conducted using marijuana with extremely high THC contents, drug clinics are beginning to see the effects.
Darryl Inaba, a director at the Haight-Ashbury Drug Clinic in San Francisco, said since the potent California marijuana became prevalent in the early 1980s, he has begun treating patients suffering from "acute anxiety reactions." At first those at the clinic assumed the marijuana was laced with PCP, Inaba said, but after testing they determined it was just high-grade pot. The patients who smoke too much strong marijuana too fast, he said, "require talk-down treatment, just like we treat a bad LSD trip."
Ten years ago people would have laughed at the idea that marijuana could cause such an adverse reaction or that users would have a difficult time giving up smoking. But now, he said, several patients a month check into the detoxification clinic because they cannot quit smoking the potent pot.
"When I was in college in the 1960s there was a lot of phony-baloney research about marijuana that was easy to poke holes in," said Ned Walsh, administrator of alcohol and drug programs in Mendocino County. "It's really unfortunate, because then people tended to dismiss anything negative about pot. But now we're finding out things that can't be ignored."
There currently are 22 million marijuana smokers in the country, according to the National Institute for Drug Abuse, and the number has stayed about the same for the last few years.
There still are many questions that remain unanswered about marijuana, and some researchers are not convinced that marijuana leads to all the health problems that have been reported.
Effects More Subtle
They are reluctant to draw conclusions between animal studies and the effect on humans; more human studies, they say, are needed. But because the effects of marijuana smoking are more subtle than other drugs, research can take years before it is conclusive.
And marijuana researchers often do not receive as much funding as those studying hard drugs. Despite the Reagan Administration's pronouncements about the problems of drug use, research funding has not kept up with the inflation rate, Cohen said.
Kevin Zeese, director of the National Organization for the Reform of Marijuana Laws (which has been fighting for legalization of marijuana since 1970), acknowledges that chronic smoking causes some health problems. But, he said, of the 22 million Americans who are at least monthly users of marijuana, only about 5% are daily smokers. And there is no evidence, he said, that smoking in moderation is harmful.
Doctors recently have been reporting a new phenomenon among pregnant women who smoke marijuana. Some are now giving birth to children who have symptoms similar to the fetal alcohol syndrome. The syndrome, previously only associated with pregnant mothers who were alcoholics, causes a number of abnormalities such as a characteristic facial appearance, deficient fetal growth, reduced central nervous functioning, mental deficiency and an increased frequency of major abnormalities.
In a study at Boston City Hospital--about 1,400 women were monitored, 15% of whom smoked marijuana--users of marijuana were five times more likely than non-users to deliver infants with features compatible with the syndrome.
Studies conducted during the past two years have concluded that marijuana use is associated with lower infant birth weight and length and a higher incidence of premature births, Cohen said. In a study at Brigham and Women's Hospital in Boston--the largest study to date--the children of mothers who smoked marijuana had five types of malformations, including congenital heart disease and spinal problems, at a rate twice as high as a control group.
Although the overall rate of all malformations was only slightly higher in the study--which surveyed about 12,000 women, 1,200 of whom smoked marijuana--the association between marijuana usage and major malformations is "suggestive" and "merits further investigation," the study concluded.
Dr. Ethel Sassenrath, a professor of behavioral biology at the UC Davis Medical School, has conducted the only controlled, long-term study of THC on a female reproductive system. In her study of rhesus monkeys, she found that the mothers who were given THC during pregnancy had a birth loss--still-births, in-utero fetal deaths and infant death just after birth--at a rate of four times higher than the drug-free group.
And in another study, Sassenrath found that fluid-filled cavities (ventricles) around portions of the brain were enlarged in the monkeys who were given THC. When cavities enlarge, she said, it means the tissues around the brain shrink.
"The enlargement was in the part of the brain which affects a number of areas like memory and integration of information--things that appear to be lacking in heavy marijuana users," she said in an interview. "This enlargement means some cell death. . . . It's wishful thinking to say that it happens on primates but it won't happen on humans."
The test group was given THC for three years and then were drug-free for a year before the tests were conducted. Although some animal tests are conducted with levels of THC comparable to that in marijuana available on the street, Sassenrath said she administered the drug with a potency equivalent to one joint a day of "marijuana like we used to see." The results probably would be exaggerated, Sassenrath said, with the more powerful marijuana.
Retained in Body Fat
Researchers say it is significant that marijuana smokers retain the drug in the system for so long. Cocaine and heroin are water soluble, quickly metabolized and usually cannot be detected by urine tests after 48 hours. But marijuana, which is fat soluble, lodges in the body's fat deposits and can be detected in chronic smokers up to 40 days after use, said Dr. Forest Tenant, a drug consultant for the California Highway Patrol and the director of Community Health Care Projects Inc., a string of Los Angeles-based drug abuse clinics.
"It's scary to think that any drug is floating around in your system that long," Tenant said. "The question is what is it doing? We can only conjecture that the health implications are not good."
The medical community is concerned about the effect of stronger strains of marijuana on people's reproductive systems. Recent primate research has revealed, Dr. Cohen said, that THC induces decreases in the "female sex hormones, estrogen and progesterone, interfering with ovulation and other hormone-related functions."
And marijuana use is associated with a reduction of the male sex hormone testosterone. The administration of THC to male mice for as little as five days, Cohen said, resulted in a reduction of sperm production and in abnormal sperm forms.
Concern for the Young
Although some of these changes are reversible when marijuana use is halted, "many questions remain about long-term use," he said. And the findings could have serious implications for adolescents who are still maturing.
Animal studies have indicated that THC also interferes with the immune system, Cohen said. In tests with guinea pigs, the drug was shown to decrease resistance to herpes simplex virus. And other studies, Cohen said, have shown that THC "appears to inhibit" the production of lymphocytes, which are important in the synthesis of antibodies.
Chronic marijuana smokers might also face a greater risk of developing lung cancer than cigarette smokers, said Dr. Donald Tashkin, a professor at UCLA Medical School who has been studying the effects of marijuana smoking since 1972. In a study of 74 subjects, Tashkin found that "even smoking one joint a day for at least two years causes abnormality of air passages and increases the effort necessary to breath by 25%."
Tashkin recently completed another study of about 275 marijuana smokers who have smoked at least two joints a day for several years. About half of the group also smoked tobacco. He conducted bronchoscope studies, which allowed him to view and biopsy samples of lung tissue.
Lung Cancer Risk
"The marijuana smokers who didn't smoke cigarettes had extensive lung changes--things you wouldn't expect to see in young individuals," Tashkin said. "They were the kinds of changes you see only in older, long-term cigarette smokers. Some of the changes could be considered precursors of lung cancer. . . . Every marijuana smoker had some kind of abnormality."
Because marijuana is smoked in a different fashion than cigarettes--marijuana is inhaled deeply and held in the lungs longer--those in the test group had damaged different parts of the throat and lungs. As a result, they could "run a greater risk of lung cancer and cancer of the larynx than tobacco smokers, even though they smoke much less." And tobacco smoking exacerbates the problem.
Tashkin found in one study that one marijuana joint does as much damage to certain lung functions as 16 cigarettes.
Some have suggested that because the marijuana on the streets is more potent now, people smoke less and decrease their risk of health problems. But, Tashkin said, just the THC is a respiratory irritant. And while the occasional users may smoke less when the potency increases, researchers say, chronic smokers generally do not.
"Marijuana smoking now is where cigarette smoking was in the 1940s," Tashkin said. "With something like smoking, you've got a pre-cancerous smoldering and it takes decades for the cancer to develop."
A study published last year by the Insurance Institute for Highway Safety conducted autopsies on 440 Southern California males who had died in traffic accidents. Thirty-seven percent recently had smoked marijuana and many of them also had consumed alcohol. The men were between the ages of 15 and 34--an age group responsible for more than half of all fatal accidents, an institute spokesman said.
"Drunk driving is bad enough," said Tenant of Community Health Projects. "But if they also smoke some of that strong marijuana, you've got accidents waiting to happen."
Many people in their 30s and 40s won't drive drunk, but they will drive after smoking marijuana, Tenant said. They still have the perception that marijuana is harmless.
Indeed, the drug they were used to smoking in college was pretty harmless, he said. "But with the stuff out now . . . it's like the difference between a light beer and a pint of whiskey."